Who made the Great Plan?

I maybe just a wee bit crazy, but after rewatching that first scene from s2e1 where Crowley is told about the Great Plan and the scene where Aziraphale debunks the Great Plan and the Ineffable Plan being the same from s1e7, I got to thinking. Even though it was a spur of the moment realization, Aziraphale was right that the Ineffable Plan and the Great Plan are two differnt things. Working off of this conclusion, I dont think it was God who made the Great Plan. While its possible that God changed the plan for the fate of the universe, its highly unlikely that this misinformation would have persisted this long without someone deliberately messing with the understanding of what the Ineffable Plan was. Also we as the audience know that the Ineffable Plan was not the Great Plan becuase after the Great Plan fails, we still get narration from God in that final scene in season 1 of the nightingale which implies that God knew the Great Plan would fail and there would be a future after the supposed 6000 year time limit.

So this begs the question who made sure the Great Plan was the main narrative being spread among the angels? It wasn't a demon since technically there were no demons at the time of that first scene in s2e1 (if i have my mental timeline right). It would have to be a someone with authority among the angles who could ensure that they had constant control of the conversation.

Metatron spread the Great Plan prophecy rumor from s1. My proof:

He is the "voice of God", so everyone would believe anything he says

He would use his authority as the spokesperson for God to spread the Great Plan among the angels who would have no reason to doubt that this wasn't the word of God

In season 1, he was very adamant about not letting Aziraphale talk to God to stop the events of Armageddon

From his conversation with Aziraphale at the end of the infamous s2e6, we can see that he well adapt in manipulation as he knows exactly what to say to Aziraphale to consider and accept the job offer.

I might just be blinded by my current hatred of metatron rn and could be overestimating his abilities, but it made some sense in my mind. The only thing i cannot really pin down is his motivation for doing this. The main two culprits for any other angel would be power or ensuring Heaven's victory. However, I think that from the position that Metatron currently sits at, these two reasons don't really make any sense since he already has a shitton power which he could use to ensure victory. The only real reason i can think of is that he wants to play God, but even then I feel there has to be something else I am missing here to fully complete the picture. I feel like this all has something to do with why God was only there in a flashback and one present day scene, but no narration this season...

but tldr I think it was Metatron manipulative ass.